Treatment of cellulosic materials with hydroxyalkyl phosphonium salts

ABSTRACT

TREATMENT OF CELLULOSIC TEXTILE MATERIALS TO IMPART CREASE AND FLAME RESISTANCE THERETO WITH HYDROXYLAKYL PHOSPHONIUM SALTS HAVING THE FORMULA:   (R-CH(-OH)-CH2-)N-P(+)(-CH(-OH)-R1)(4-N) Z(-)   WHEREIN N IS A NUMBER FROM 2 TO 3, Z IS THE ANION OF A SALT-FORMING ACID, R IS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN AND LOWER ALKYL GROUPS CONTAINING FROM 1 TO 2 CARBON ATOMS AND R, IS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN AND LOWER ALKYL GROUPS CONTAINING FROM 1 TO 3 CARBON ATOMS.

United States Patent U.S. Cl. 8-120 10 Claims ABSTRACT OF THE DISCLOSURE Treatment of cellulosic textile materials to impart crease and flame resistance thereto with hydroxyalkyl phosphonium salts having the formula:

(R([11I(JH) wherein n is a number from 2 to 3, Z is the anion of a salt-forming acid, R is selected from the group consisting of hydrogen and lower alkyl groups containing from 1 to 2 carbon atoms and R, is selected from the group consisting of hydrogen and lower alkyl groups containing from 1 to 3 carbon atoms.

This application is a divisional application of Ser. No. 543,081, filed Apr. 18, 1966, now U.S. Pat. No. 3,452,098.

This invention relates to novel hydroxyalkyl phosphonium compounds and more particularly it relates to novel hydroxyalkyl phosphonium halide compounds, their method of preparation and their use for treating cellulosic textile materials to render them crease and flame resistant In the past, it has been known to form ethers by alkylating phosphonium halide materials, such as tetra'kis(hydroxyorgano)phosphonium halide, which reactions have been carried out under acidic conditions, generally using equal molar amounts of the phosphonium halide component with the alkylene oxide in the reaction. Although the resulting ether compounds have been reported as having some effectiveness as flame-retarding agents for treating cellulosic material, effectiveness has not been found to be sufliciently great, particularly in view of their cost, to warrant the widespread adoption of such materials for flame retarding purposes. Additionally, attempts to utilize such ethers for imparting crease or wrinkle resistance to cellulosic textiles has not been successful.

It has further been proposed in the past to react a tris- (hydroxymethyl)phosphine with an alkylene oxide, using equal molar amounts of the alkylene oxide and the phosphine, generally under acidic conditions. Here again, although the products obtained have some utility in the treatment of cellulosic textiles to render them flame retardant, the materials have not been found to be effective in imparting crease resistance to the fabric and like the ether products described hereinabove, have not been widely used. Additionally, the tris (hydroxymethyl)phosphine is normally a difficult material to handle, being readily oxidized in the air and, thus, normally requiring handling in an inert atmosphere. Accordingly, because of these difficulties, these reaction products have not been used, even for imparting flame retardancy, to any great extent.

It is, therefore, an object of the present invention to provide novel hydroxyalkyl phosphonium compounds, use- 3,552,909 Patented Jan. 5, 1971 ICC ful in treating cellulosic textile material to impart crease and flame resistance thereto.

A further object of the present invention is to provide a novel method for preparing hydroxyalkyl phosphonium compounds, which method does not utilize reactants which are difficult to handle.

Another object of the present invention is to provide a method for treating cellulosic textile materials so as to impart flame and crease resistance to these materials.

These and other objects will become apparent to those skilled in the art from the description of the invention which follows:

Pursuant to the above objects, the present invention includes a hydroxyalkyl phosphonium halide having the formula P+Z- RCHCH2 a wherein n is a number from 2 to 3 and Z is the anion of a salt forming acid, and R is a lower alkyl group containing 1 to 3 carbon atoms and R is selected from the group consisting of hydrogen and lower alkyl groups containing 1 to 3 carbon atoms.

More specifically, the hydroxyalkyl phosphonium salts of the present invention are those compounds containing at least two Z-hydroxyalkyl groups, and desirably three 2-hydroxyalkyl groups. Exemplary of specific compounds falling within this class are di(2-hydroxyethyl)di(hydroxymethyl) phosphonium chloride; tris(2-hydroxyethyl)hydroxymethyl phosphonium chloride; tris(2-hydroxybutyl) hydroxymethyl phosphonium chloride; tris(2-hydroxypropyl)hydroxymethyl phosphonium chloride; di(2-hydroxylethyl) di(hydroxyethyl)phosphonium chloride; tris(2-hydroxyethyl)hydroxybutyl phosphonium chloride and the like. It is to be appreciated, that in these compounds, the acid anion may be that of any suitable acid which will form a salt with the compound, such as chloride, bromide, iodide, fluoride, acetate, sulfate, and the like. Of these, the preferred anion is the chloride and specific reference hereinafter Will be made to this material.

The hydroxylalkyl phosphonium salts of the present invention are prepared by reacting a neutralized tetrakis (hydroxyalkyl)phosphonium halide with an alkylene oxide. The tetrakis(hydroxyalkyl)phosphonium halide used in this reaction has the formula wherein R is selected from the group consisting of hydrogen and lower alkyl groups having from 1 to 3 carbon atoms and wheretin X is halogen. Preferably, the phosphonium halide is tetrakis(hydroxymethyl)phosphonium chloride although other phosphonium halides such as tetrakis (hydroxymethyl)phosphonium chloride; tetrakis(hydroxybutyl)phosphonium bromide; tetrakis(hydroxypropyl)phosphonium chloride; and the like, may also be used. The preferred tetrakis (hydroxymethyl)phosphonium chloride is commercially available, typically as an aqueous solution. Moreover, it can be safely and conveniently handled, in air, either as a crystalline solid, having a melting point of about centigrade, or as an aqueous or non-aqueous solution. For these reasons, this is the preferred phosphonium halide compound for use in the present invention.

The alkylene oxide used in forming the novel phosphonium compounds of the present invention has the formula:

wherein R is selected from the grouping consisting of hydrogen and lower alkyl groups containing from 1 to 2 carbon atoms. Of the various alkylene oxides which may be used, the preferred one has been found to be ethylene oxide although, in many instances, satisfactory results have been obtained when using propylene and butylene oxide as well.

In carrying out the process of the present invention, the preferred tetrakis(hydroxymethyl)phosphonium chloride is reacted with an excess of the preferred ethylene oxide in the presence of a base, whereby neutralization of the phosphonium chloride material is effected, in situ, in the reaction. In carrying out the reaction, the ethylene oxide should be present in an amount of at least 2 moles of ethylene oxide per mole of the tetrakis(hydroxy methyl)phosphonium chloride and is preferably present in an amount of at least 3 or more moles of ethylene oxide per mole of the phosphonium chloride. Preferably, the base may first be reacted with the phosphonium chloride and thereafter the resulting neutralized material is reacted with the ethylene oxide.

While it is not intended to limit the present invention to a particular theory of reaction, the following equation is presented to illustrate the preparation of the compounds of the present invention, in terms of the stoichiometry for a typical specific embodiment thereof:

(l) in; noon-.1 (01120112011 11,0

It is to be noted, that in order to form the hydroxyalkylphosphonium salt of the present invention, this reaction must be carried out at a pH of at least about 5 and preferably at a pH within the range of about 8 to 9. Accordingly, sufficient base will be provided in the reaction to obtain this pH. Additionally, it is to be noted that at a pH above about 10, it has been found that oxidation of trivalent phosphorus takes place, which reaction is detrimental to the formation of compounds of the present invention. Accordingly, in order to prevent the pH of the reaction mixture from exceeding a value of about 10, an acid is added to the reaction media to control the pH. This acid will react with the phosphonium hydroxide product (I) formed, forming the salt (II) of the acid and the phosphonium hydroxide compound, which salt is then recovered as the product of the present process.

As has been indicated hereinabove, various acids may be used for this purpose to form the salts, including hydrochloric acid, hydrobrornic acid, hydroiodic acid, hydrofluoric acid, sulfuric acid, acetic acid, and the like. In many instances, the preferred acid has been found to be hydrochloric acid and for this reason, specific reference hereinafter will be made to this material. Accordingly, when using hydrochloric acid, the preferred product produced by the method of the present invention will be tri (2-hydroxyethyl)hydroxymethyl phosphonium chloride.

Among the bases which may be employed in the reaction of the present invention are the various alkali metal hydroxides, oxides, carbonates, bicarbonates, as well as tertiary amines, quaternary ammonium hydroxide, and, in general, any strong base which is capable of forming hydroxide ions in aqueous solution. It will be apparent from the equation presented hereinabove, that in the reaction, the base functions as a reactant, rather than as a catalyst and is consumed in the reaction in an amount which is proportional to the quantity of the phosphonium halide material which is employed. Accordingly, in many instances, it is preferred to employ the base in an amount which is about equivalent, on a molar basis, to the amount of the tetrakis(hydroxymethyl) phosphonium chloride which is used.

The reaction of the present invention may conveniently be accomplished in either aqueous or non-aqueous media. Exemplary of the mediums which may be used are water; non-aqueous liquids such as methyl alcohol, ethyl alcohol, propyl alcohol, dimethyl formamide, acetonitrile; and mixtures of water and a non-aqueous liquid. In most instances, however, it is preferred to employ an aqueous medium. Normally, the reaction time will vary from less than a minute to more than an hour, depending upon the temperatures, proportion of reaction, and the like. Typically, the reaction temperatures will be maintained at not substantially in excess of about 50 Centigrade, so as to avoid too vigorous a reaction with the consequent possibility of volatilizing the reaction constituent and undesired side reactions.

Preferably, the reaction is carried out by first neutralizing the tetrakis(hydroxymethyl)phosphonium chloride with the base, and thereafter, adding to the neutralized phosphonium chloride the ethylene oxide in the amounts which have been indicated hereinabove. By controlling the rate of addition of the ethylene oxide to the neutralized phosphonium chloride, the reaction temperature may normally be maintained below the desired 50 centigrade, and by continuous addition of mineral acid, the pH may be kept within the preferred range of 8-9. Inasmuch as the reaction is exothermic, in some instances, it may be desirable to provide external cooling for the reaction. The hydroxyalkyl phosphonium salts formed by the present reaction are separated from volatile components by a vacuum stripping and from the salt by-prodnot by extraction with alcohol or similar solvent. Distillation of the extracting solvent then alfords the phosphonium salt as the product. Additionally, it has been found that in some instances, it may be desirable to carry out the reaction under pressure.

The hydroxyalkyl phosphonium salts of the present invention may be used in the treatment of cellulosic textile materials so as to impart crease or wrinkle resistance as well as flame resistance to the treated materials. The present phosphonium salts may be applied to the textile materials in any suitable formulation, as for example, an emulsion, a dispersion or a solution. These may be applied by dipping, spraying, rolling, or by the use of a textile pad bath, or other suitable techniques. Following the application of the textile treating solution, the excess may be removed by squeezing, centrifuging, pressing, or other operations and, if desired, the materials may then be dried in any convenient manner, such as in a forced air oven, under infrared lamps, or by evaporation in air at room temperature. The treated cloth is then cured, that is, reacted with the modifying agent, by holding it for a period of time at an elevated temperature in the presence of a basic catalyst. As is the case with most textile modifying agents, the addition of excessive amounts may result in a decrease in the tensile strength of the treated material, the tensile strength being an inverse function of the amount of modifying agent employed. With low percentages of the modifying agents of the present invention, the loss in tensile strength is quite small. For practical purposes, the amount of modifying agent used will be such as to result in a low loss of tensile strength while still providing high. wrinkle and crease resistance as well as flame resistance.

Based on the foregoing, it has been found that on add on of the modifying agent of from about 1 to 20% by weight will be satisfactory for most purposes. It is to be appreciated that the term add-on as used herein refers to the modifying agent which has reacted with the textile material, that is, the modifying agent which remains as an integral chemical part of the textile material, after curing and washing to remove unreacted excess. The amount of add-on is given in percent by weight based on the original dry weight of the textile material. It has been found that good wrinkle resistance is imparted to the textile materials when add-ons within the range of about 3 to 10% are used, while good flame resistance is provided with add-ons within the range of about 5 to 20%. Accordingly, in most instances, to obtain the desired wrinkle and flame resistant properties, add-ons within the range of about 5 to are preferred.

In formulating textile treating compositions utilizing the phosphonium salts of the present invention, it is preferable to formulate these materials as aqueous solutions. If desired, however, an emulsion dispersion or solution is a suitable non-aqueous solvent, such as an alcohol, or the like, may be used. Typically, the treating solutions are formulated so as to contain the phosphonium salt of the present invention in an amount within the range of about 1 to about 40% by weight of the solution and preferably in an amount within the range of about 10 to about by weight of the solution.

Additionally, the treating solutions may also contain a basic catalyst which is employed to assist the reaction between the phosphonium salts of the present invention and the textile material. When incorporated in the treating solution, these catalysts are preferably present in amounts which will provide a pH in the treating solution which is greater than about 7 and preferably a pH within the range of about 8 to 11. Alternatively, the basic catalyst may be applied in a separate step either before or after the application of the phosphonium salt of the present invention.

Basic catalysts which may be employed include, for example, alkali metal or other suitable hydroxides, carbonates, bicarbonates, acetates, phosphates, metasilicates, and the like. Particularly suitable catalyst materials have been found to be sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate. Where these materials are added to the textile treating solution, they are preferably present in amounts within the range of about 0.5 to about 20% by weight of the composition.

After the textile material has been treated with the present solution and the excess solution has been removed therefrom, it is cured at a temperature within the range of about 20 centigrade to about 250 centigrade, for a period of time suflicient to permit the reaction between the phosphonium compound and the textile material to take place. The curing time may vary from several hours, at room temperature, to less than 1 minute when elevated temperatures are used. In many instances, excellent curing results have been obtained when using curing temperatures within the range of about 150 to 185 degrees centigrade for a period of from about 3 to 10 minutes.

If desired, the treatment with the hydroxyalkyl phosphonium salts of the present invention may be supplemented by treatment with other materials for modifying or softening the hand of the material, water repellent agents, dyestuffs or the like, as are known to those in the art. These materials may be added simultaneously, in the same formulation as the hydroxyalkyl phosphonium salts, or they may be applied to the fabric either before or after the application of these salts, in a separate operation.

In order that those skilled in the art may better understand the present invention and the manner in which it may be practiced, the following specific examples are given. In these examples, unless otherwise indicated, temperatures are in degrees centigrade and parts and percents are by weight. It is to be appreciated, however, that these examples are merely exemplary of the present invention and are not to be taken as a limitation thereof.

6 EXAMPLE 1 To a reaction vessel, provided with a magnetic stirrer and cooled by an ice bath, was added 238 grams (1.0 mole) of an aqueous solution of tetrakis(hydroxy- 1nethyl)phosphonium chloride in grams of boiled water. The reaction vessel was flushed with nitrogen and there was then added a solution of 5 3 grams (0.81 mole) of 86% potassium hydroxide pellets in grams of boiled water, while the reaction mixture was stirred. Thereafter, ethylene oxide, partially diluted with nitrogen, was bubbled through the reaction mixture while the temperature was maintained within the range of 23 to 42 degrees centigrade. Additionally, a solution of 97 grams (1.0 mole) of concentrated hydrochloric acid in 97 grams of boiled water was added portion-wise to the reaction mix ture to maintain the pH within the range of 8-9 during the reaction. After the passage of 210 grams (4.77 moles) of ethylene oxide through the reaction mixture, the flow of ethylene oxide was stopped and a stream of nitrogen was blown through the reaction vessel for 50 minutes to remove unreacted ethylene oxide. Thereafter an additional quantity of hydrochloric acid solution was added to the reaction mixture to bring the solution to a final pH of about 7.0. The reaction solution was then concentrated in vacuum to a salty slurry to which was added 500 milliliters of denatured anhydrous alcohol. The mixture was agitated and filtered to remove potassium chloride. The clear filtrate was then concentrated to substantially constant weight at a temperature of 45 centigrade and a pressure of 16 millimeters of mercury. 254 grams of a pale yellow mobile liquid product having an iodine equivalent weight of 144 and a phosphorus content of 11.44%, of which 85.2% was non-volatile at 72 centigrade and a pressure of 0.2 millimeter, was obtained. From this material, an anhydrous product was isolated as a viscous, amber oil by concentrating to constant weight at a temperature of 60 to 70 centigrade and a pressure of 0.2 millimeter of mercury. It was determined that 3.44 moles of ethylene oxide per mole of tetrakis(hydroxymethyl) phosphonium chloride was reacted in forming this product and that approximately 3 moles of formaldehyde, per mole of the phosphonium chloride had been released. This anhydrous product, determined to be tris( 2-hydroXy-ethyl) hydroxymethyl phosphonium chloride had an iodine equivalent weight of 124, an acid equivalent weight of 242, and contained 13.33% phosphorus, as compared to the theoretical phosphorus content of 13.32%. Additionally, the ratio of combined formaldehyde to phosphorus was 1 and the tetraphenylboron derivative analyzed correctly for all elements.

EXAMPLE 2 The procedure of Example 1 was repeated with the exception that 1.25 moles of tetrakis(hydroxymethyl)phosphonium chloride and 1.01 moles of potassium hydroxide were used. Additionally, the pH of the reaction was maintained within the range of about 9 to 10 and a total of about 1.13 moles of hydrochloric acid was used to maintain this pH and effect the neutralization of the reaction product to a pH of 7. A total of 4.12 moles of ethylene oxide were passed into the reaction mixture and it was found that in forming the reaction product, 2.71 moles of ethylene oxide were reacted. The product formed was determined to be a mixture of di(2-hydroxyethy1)di(hy droxymethy1)phosphonium chloride and tris(2-hydroxyethyl)hydroxymethyl phosphonium chloride.

When the procedure of the above examples is repeated using tetrakis(hydroxyethyl)phosphonium bromide, the product obtained is tris(2-hydroxyethyl)hydroxyethyl phosphonium chloride and when the procedure is repeated using propylene oxide, the product obtained is di(2-hydroxypropyl di hydroxymethyl phosphonium chloride. Additionally, when the procedure of the above example is repeated but using sulfuric acid and acetic acid, in place of the hydrochloric acid, similar products are obtained,

with the exception that the products are the phosphonium sulfate and phosphonium acetate, respectively, rather than the chloride.

When the procedure of the above examples is repeated but without the addition of the base, so that the pH of the reaction medium is below 5, there is substantially no replacement of formaldehyde in the reaction even when more than 1 mole of ethylene oxide per mole of tetrakis (hydroxymethyl) phosphonium chloride is reacted, thus indicating a different reaction mechanism and reaction products than are formed in the above examples wherein formaldehyde is replaced by the ethylene oxide.

EXAMPLE 3 A textile pad bath was formulated containing 25% by weight of the tris(2-hydroxyethyl)hydroxymethyl phosphonium chloride as prepared in Example 1, in water. This treating solution also contained 3% by weight of sodium carbonate, as the curing catalyst. Bleached, desized, mercerized, -80 x 80 (threads per inch) cotton cloth, weighing 3.1 ounces per square yard was padded through the treating solution to effect a wet pick up of about 80%. The thus-treated cloth was then cured by heating for 10 minutes at about 155 centigrade to provide a final resin add-on on the cloth of 9.7%, after washing in hot soapy water, rinsing and pressing dry and flat. The wrinkle recovery angles of the cloth were then determined using the Monsanto method, and the wrinkle recovery angles in the fill direction were found to be 108, dry and 134, wet, as compared to 67, dry, and 83, wet, for an untreated control. Samples of the treated cloth were then subjected to the flammability test, American Association of Chemists and Colorist Test AATCC 33-1957, and it was found that 24 seconds were required for the flame to travel 5 inches up a strip held at a 45 degree angle, as compared to a time of only 9 seconds for an untreated control. Additionally, it was found that on the treated sample there was no flame propagation in a downward or horizontal direction although such propagation was obtained on the untreated control sample.

EXAMPLE 4 The procedure of Example 3 was repeated with the exception that the treating solution used was an aqueous solution containing 14% of the tris(2-hydroxyethyl)hydroxymethyl phosphonium chloride as prepared in Example 1 and 6% by weight of sodium bicarbonate as a curing catalyst. After curing as in Example 3, a resin addon of 9.0% was obtained and the wrinkle recovery angles in the fill direction were found to be 107, dry and 122,

wet, as compared to 68, dry, and 60, wet, for an untreated control.

While there have been described various embodiments of the invention the methods and compositions described are not intended to be understood as limiting the scope of the invention, as it is realized that changes therewithin are possible and it is further intended that each element recited in any of the following claims is to be understood as referring to all equivalent elements for accomplishing substantially the same results in substantially the same or equivalent manner, it being intended to cover the invention broadly in whatever form its principle may be utilized.

What is claimed is:

1. A method of treating cellulosic textile materials to impart wrinkle, crease, and flame resistance thereto which comprises treating said material with a basic catalyst and hydroxyalkyl phosphonium salts having the formula:

I. OH

wherein n is a number from 2 to 3, Z is the anion of a salt-forming acid, R is selected from the group consisting of hydrogen and lower alkyl groups containing from 1 to 2 carbon atoms, and R is selected from the group consisting of hydrogen and lower alkyl groups containing from to 3 carbon atoms, in an amount sufiicient to provide a treated material having at least about 1 percent by weight of said hydroxyalkyl phosphonium salt chemically reacted therewith, said weight based upon the original dry weight of the textile material to be treated.

2. A method as claimed in claim 1 wherein the amount of hydroxyalkyl phosphonium salt chemically reacted with the cellulosic material is from about 1 to about 20 percent by weight.

3. A method as claimed in claim 1 wherein the hydroxyalkyl phosphonium salt is applied to the cellulosic material as an aqueous solution containing said salt in an amount of from about 1 to about 40 percent by weight based on the weight of the solution.

4. A method as claimed in claim 1 wherein the basic catalyst is selected from the group consisting of alkali metal hydroxides, carbonates, acetates, bicarbonates, phosphates and metasilicates.

5. A method as claimed in claim 1 wherein the cellulosic material is treated with a solution containing the hydroxyalkyl phosphonium salt and the basic catalyst.

6. A method as claimed in claim 5 wherein the basic catalyst is present in an amount of from about 0.5 to about 20 percent by weight of the composition.

7. A method as claimed in claim 1 wherein the basic catalyst is sodium carbonate.

8. A method as claimed in claim 3 wherein the pH of the solution is from about 8 to about 11.

9. A method as claimed in claim 1 wherein the hydroxyalkyl phosphonium salt is tris(2-hydroxy-ethyl) hydroxymethyl phosphonium chloride.

10. A wrinkle resistant cellulosic textile material prepared in accordance with the procedure of claim 1.

References Cited UNITED STATES PATENTS 1/ 1969 Grayson 8120 6/1969 Vullo 117136X US. Cl. X.R.

UNITED STATES PATENT OFFIQE CERTIFICATE OF CORRECTION Patent No. 3 ,552 909 Dated January 5 1971 InVentor( J. Vullo It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2 line 39: correct "hydroxylethyl" to read ---hydroxyethy1--- Column 2 line 58: correct "wheretin" to read ---wherein-- Column 8 line 17 correct "from to" to read ---from 1 to Signed and sealed this 20th day of April 1971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents 

